The Ballard Spur… As a Gondola Line.

There’s an idea going around (read the comments here) that a logical extension of Link in Seattle would be to just make a turn West at Brooklyn Station, and serve Wallingford, Phinney or Fremont, and Ballard. This is a great idea, and a way of serving some high-demand routes with our new rail infrastructure. However, there are some significant barriers to implementing this plan: we’re out of planned train capacity in the downtown tunnel, it’s claimed Northgate needs all of this capacity, branching a major trunk is rarely a good idea, and there would be two deep (expensive) stations. Conventional wisdom is to save our pennies and someday serve Ballard with its own light rail line coming up from downtown. There are benefits and disbenefits to both strategies, and I don’t plan on settling the debate here.

But consider for a moment running a gondola spur line. We can have high capacity, very high frequency transit without giving up train capacity in the downtown tunnel. We provide future connectivity between the current and future light rail lines, if one is built. We give at least 18,500 riders (the 44, 15, 18) a faster way around each day. And we do it all for much less money than a light rail line.

Let’s run the numbers for converting this spur to a gondola line:

At 3.2 miles, if we use a single cable gondola (14mph) that’s about a 15 minute journey. That’s probably too slow. So let’s pull out the big guns and go with a 3S system (two support cables, one drive cable, 24mph). Now we’re looking at 8 minutes, plus time at stops, so about 10 minutes end to end. That’s more like it.

Looking at capacity, a 3S system will have plenty. We can get between 4,000 and 6,000 passengers per hour per direction (and possibly more). That’s the equivallent to between 40 and 60 buses in each direction each hour.

Uncongested speed of a freeway lane is about 2000 vehicles per hour per lane (powerpoint file). Assuming 1.5 passengers per vehicle (probably high), this is about the same as 4 lanes of freeway (2 in each direction).

Is there anywhere in the world that has a multiple-station gondola line in an urban environment running over a street that’s not on a steep hill? I’m not saying that that’s a reason not to do it, but it’s hard to convince a transit agency to do something that’s never been done before.

I don’t see how a lack of a steep hill would be at all an impediment. That said, I don’t know of any (though there are many examples of gondolas with flat sections). However, there just aren’t many urban gondola systems in the world, so in the next few decades it won’t be hard to be the first at something.